Question: Mu is walking laps to raise money for charity. For each lap she walks, her sponsors will donate $\$7$. Mu has walked $l$ laps and raised a total of $\$105$. Write an equation to describe this situation. How many laps has Mu walked?
Mu has raised a total of ${\$105}$. Her sponsors will donate ${\$7}$ for each lap, with ${l}$ laps walked. We can find out how many laps Mu has walked by finding the quotient: ${l}=\dfrac{{105}}{{7}}$ Other ways to represent the situation with an equation include: $\dfrac{{105}}{{l} }={7}$ or ${7}{{l}}={105}$. Now we can solve for ${l}$. Since $ l$ is already by itself, we can solve by dividing $\dfrac{{105}}{{7}}$. $\begin{aligned} l &= \dfrac{{105}}{{7} } \\ \\ l &={15} \end{aligned}$ The following equation matches this situation: $ l = \dfrac{105}{{7} }$ Mu has walked $15$ laps.